Neural microelectrodes (NEs) are a powerful tool for electrically interfacing with neural systems in-vivo, enabling scientific studies of cortical systes as well as brain-machine interfaces (BMI). However, a significant challenge for NEs is to retain chronic function, since the implantation and chronic presence of these neural interface devices can induce a cascade of biological processes that ultimately isolate the NEs from the neural system. Bioactive materials from natural brain extracellular matrix (ECM) are found to promote neural ingrowth and regeneration, and support a series of reactions stabilizing neural function. Recently, microfabrication technologies have been developed that enable the realization of electrodes comprised primarily from ECM materials, with sufficient complexity to enable insertion into and recording from cortical neural systems in-vivo. We hypothesize that due to their bioactivity and mechanosimilar properties, such ECM-based NEs will exhibit longer duration of functionality in chronic implant scenarios compared to their conventional inorganic counterparts. We propose to develop minimal-injury ECM-based NEs, achieve initial understanding of the behavior of ECM-based NEs in vivo, and assessing the chronic durability of ECM-based NEs compared to inorganic controls. We believe that understanding the electrical, mechanical and biological performance of ECM-NEs will enable neural interface devices which are capable of sustained and reliable performance in vivo. The proposed program sits at the intersection of the disciplines of neuroengineering, electrical engineering, and microfabrication technology. It will be carried out primarily by two postdoctoral associates under the supervision of three faculty - one with significant experience in neuroengineering and neural interface materials; one with significant experience in chronic recording from neural systems; and one with significant experience in microfabrication technology, especially as applied to biological systems and applications. We expect this program to last two years and provide fertile ground for additional work in the areas of (1) protein- based interfaces to the brain; and (2) micro- and nanofabrication technology.